This is really great. I'm not usually a fan of fiction that's based on comedic material. The fics rarely tend to capture the humor and timing of the original show. But here, I think, you really do your best to get that. The dialogue is nice and humorous, and your final sentence is hilarious; it definitely shows who Dan is in comparison to Casey.

Your characterization is spot on. I could totally hear Natalie say those things in my head - despite the fact that the show hasn't been on in years. That you were able to capture the essence of the show, Aaron Sorkin's words, and the characters in such a short fic is really a testament to your abilities. Great job.